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Rispri LabsENGINEERING A CIRCULAR FUTURE

Free tool · Water conservation

Water Demand Calculator (CPHEEO)

Daily water demand = population × per capita supply (LPCD) + other demands, increased for distribution losses. CPHEEO norms are 135 LPCD for cities with sewerage and 150 LPCD for metros. A township of 10,000 people at 135 LPCD needs about 1.59 MLD including 15% losses.

Your inputs

Results update as you type. Example values are filled in.

L/person/day
m³/day
%

CPHEEO asks utilities to limit losses to 15%.

% per year
years

Use 0 for today. CPHEEO uses 30 years for most works.

How to use this calculator

  1. Enter the population served.
  2. Choose the area type to set the CPHEEO per capita norm, or enter your own.
  3. Add other demands and the expected losses.
  4. Set growth and design period to size for the future.

How is water demand calculated in India?

Pn = P0 × (1 + r)n

Net demand = Pn × LPCD ÷ 1,000 + other

Gross supply = net ÷ (1 − losses)

Peak factor for distribution mains follows the CPHEEO Manual: 3.0 up to 50,000 people, 2.5 up to 2 lakh, 2.0 above that.

Worked example

With present population 10,000, type of area: City or township with sewerage (135 LPCD), per capita supply 135 L/person/day, other demand (commercial, institutional, fire) 0 m³/day, distribution losses (non-revenue water) 15 %, population growth 1.5 % per year, design period 0 years:

Water demand incl. losses: 1.588 MLD

The calculator also gives design population 10,000 persons; net demand at consumers 1,350 m³/day; gross supply incl. losses 1,588 m³/day.

Assumptions and limits

  • Geometric growth; a census based projection is better for large schemes.
  • Storage of one third of daily supply is a common rule of thumb, not a substitute for a mass curve.
  • Fire demand is not added automatically.

Frequently asked questions

What is the standard water requirement per person in India?

CPHEEO recommends 135 litres per person per day for cities with sewerage, 150 LPCD for metropolitan cities, 70 LPCD for towns without sewerage, and the Jal Jeevan Mission targets 55 LPCD for rural households.

What is peak factor in water supply?

It is the ratio of peak hourly flow to average flow. Distribution pipes are sized for peak flow because people use most water in the morning and evening.

How much water does an apartment building need?

Multiply residents by 135 to 150 LPCD. A 100 flat building with 4 people per flat needs about 54 to 60 m³ a day, plus losses and common area use.

References

  • CPHEEO, Manual on Water Supply and Treatment (1999)
  • BIS IS 1172:1993, Code of basic requirements for water supply, drainage and sanitation
  • Jal Jeevan Mission operational guidelines

Built and maintained by the Rispri Labs engineering team. Last updated .